EP0204305A2 - Four-wheel steering system for automotive vehicles - Google Patents
Four-wheel steering system for automotive vehicles Download PDFInfo
- Publication number
- EP0204305A2 EP0204305A2 EP86107496A EP86107496A EP0204305A2 EP 0204305 A2 EP0204305 A2 EP 0204305A2 EP 86107496 A EP86107496 A EP 86107496A EP 86107496 A EP86107496 A EP 86107496A EP 0204305 A2 EP0204305 A2 EP 0204305A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- wheel steering
- axis
- steering mechanism
- bell crank
- response
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
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Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B62—LAND VEHICLES FOR TRAVELLING OTHERWISE THAN ON RAILS
- B62D—MOTOR VEHICLES; TRAILERS
- B62D7/00—Steering linkage; Stub axles or their mountings
- B62D7/06—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins
- B62D7/14—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins the pivotal axes being situated in more than one plane transverse to the longitudinal centre line of the vehicle, e.g. all-wheel steering
- B62D7/15—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins the pivotal axes being situated in more than one plane transverse to the longitudinal centre line of the vehicle, e.g. all-wheel steering characterised by means varying the ratio between the steering angles of the steered wheels
- B62D7/1518—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins the pivotal axes being situated in more than one plane transverse to the longitudinal centre line of the vehicle, e.g. all-wheel steering characterised by means varying the ratio between the steering angles of the steered wheels comprising a mechanical interconnecting system between the steering control means of the different axles
- B62D7/1527—Steering linkage; Stub axles or their mountings for individually-pivoted wheels, e.g. on king-pins the pivotal axes being situated in more than one plane transverse to the longitudinal centre line of the vehicle, e.g. all-wheel steering characterised by means varying the ratio between the steering angles of the steered wheels comprising a mechanical interconnecting system between the steering control means of the different axles comprising only mechanical parts, i.e. without assistance means
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
- Y10T—TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION
- Y10T74/00—Machine element or mechanism
- Y10T74/16—Alternating-motion driven device with means during operation to adjust stroke
- Y10T74/1625—Stroke adjustable to zero and/or reversible in phasing
Definitions
- the present invention relates to a steering system for an automotive vehicle having two pairs of dirigible road wheels, and more particularly to a rear wheel steering mechanism adapted for use in a four-wheel steering system capable of steering the dirigible rear road wheels in response to steering operation of the dirigible front road wheals.
- a linkage such as a rotary shaft or a reciprooable link arranged in a fore-and-aft direction of the vehicle and drivingly connected at its front end to a front wheel steering mechanism to be moved in response to steering operation thereof, and a connecting mechanism arranged to drivingly connect the linkage to an operation rod of a rear wheel steering mechanism in such a manner that the operation rod is displaced in an axial direction in response to movement of the linkage to steer the dirigible rear road wheels.
- the connecting mechanism includes an input shaft in drive connection to the linkage for rotation therewith, an output shaft swingably connected at its one end to the input shaft by means of a universal joint and being integrally connected at its other end with an operation rod of the rear wheel steering mechanism, and drive means arranged to incline the output shaft with respect to the input shaft.
- an inclined angle of the output shaft with respect to the input shaft is controlled by activation of the drive means to vary the steering angle ratio and direction of the rear road wheels.
- the operation rod of the rear wheel steering mechanism is inevitably displaced in an axial direction even when the input shaft is being stat:onary. This causes change in the alignment, particularly toe-in, of the rear road wheels, resulting in deterioration of the steering stability of the vehicle.
- a primary object of the present invention to provide an improved connecting mechanism adapted for use in combination with the rear wheel steering mechanism, wherein the steering angle and direction of the rear road wheels relative to those of the front road wheels ear be controllod without oaucing any change in the alignment of the rear road wheels.
- a secondary object of the present invention is to provide an improved ccnnecting mechanism, having the above-described characteristics, wherein the ratio of the steering angle of the rear road wheels relative to that of the front road wheels can be controlled in accordance with the vehicle speed.
- the foregoing objects are accomplished by providing a connecting mechanism assembled in combination with the rear wheel steering mechanism and being drivingly connected to the front wheel steering mechanism through a linkage for effecting axial movement of an operation rod of the rear wheel steering mechanism in response to operation of the front wheel steering mechanism.
- the connecting mechanism comprises a housing arranged to fixedly mounted on a body structure of the vehicle, a carrier rotatably mounted within the housing and being arranged to rotate about a first axis perpendicular to the axis of the operation rod, drive means mounted on the housing to effect rotary motion of the carrier about the first axis, a bell crank rotatably mounted on the carrier and arranged to rotate about a second axis coaxial or in parallel with the axis of the operation rod when the carrier is retained in a neutral position, the bell crank having a first arm extending therefrom at a predetermined angle to the first axis and a second arm extending therefrom along the first axis, a first link having one end pivotally connected vith the first arm of the bell crank and the other end operatively connected to the linkage to be moved along the first axis in response to operation of the front wheel steering mechanism, and a second link pivotally connected with the second arm of the bell crank and operatively connected to the operation rod.
- the connecting mechanism further comprises an input shaft rotatably mounted within the housing and being drivingly connected to the front wheel steering mechanism through the linkage to be rotated in response to operation of the front wheel steering mechanism, and a slider slidably mounted within the housing along the first axis and pivotally connected to the other end of the first link, the slider being operatively connected to the input shaft to be reciprocated along the first axis in response to rotation of the input shaft.
- FIG. 1 there is schematically illustrated an automotive vehicle equipped with a four-wheel steering system which comprises a front wheel steering mechanism 10 interconnected with a rear wheel steering mechanism 20 by means of a linkage 30.
- the front wheel steering mechanism 10 is in the form of a well-known steering mechanism which includes a rack bar 11 arranged to be axially displaced by operation of a steering wheel WS, a pair of tie rods 13 each connected to opposite ends of rack bar 11, and a pair of knuckle arms 12 each connected to the tie rods 13 to steer a pair of dirigible front road wheels WF in response to axial displacement of the rack bar 11.
- a rack bar 11 arranged to be axially displaced by operation of a steering wheel WS
- tie rods 13 each connected to opposite ends of rack bar 11
- a pair of knuckle arms 12 each connected to the tie rods 13 to steer a pair of dirigible front road wheels WF in response to axial displacement of the rack bar 11.
- the rear wheel steering mechanism 20 includes a pair of operation rods 21 arranged to be displaced along with a lateral axis L 1 , a pair of tie rods 23 each connected to the operation rods 21, and a pair of knuckle arms 22 each connected to the tie rods 23 to steer a pair of dirigible rear road wheels WR in response to axial movement of the operation rods 21.
- the linkage 30 includes a main rotary shaft 31 arranged in a fore-and-aft direction of the vehicle and rotatably supported on a body structure of the vehicle.
- the main rotary shaft 31 has one end drivingly connected to a front pinion shaft 34 through an intermediate shaft 32 and the other end drivingly connected through an intermediate shaft 33 to a connecting mechanism A assembled in combination with the rear wheel steering mechanism 20.
- the front pinion shaft 34 is drivingly connected to the rack bar 11 to be rotated in response to axial displacement of the rack bar 11.
- the connecting mechanism A comprises a housing 40'fixedly mounted on the vehicle body structure, an input shaft 41 rotatably supported by a pair of axially spaced ball bearings 51, 52 mounted within housing 40 and being arranged in drive connection to the linkage 30, a sector gear 42 pivotally mounted within housing 40 at its axis part 42a, a slider 43 axially slidably mounted within a cylindrical bore 40a of housing 40 the axis L 2 of which is located in the fore-and-aft direction of the vehicle and perpendicularly to the axis L 1 of operation rods 21, a cylindrical carrier 44 rotatably supported by a pair of axially spaced ball bearings 53, 54 mounted within housing 40 and being arranged to rotate about the axis L 2 of slider 43, and a drive means 45 mounted on the housing 40 to effect rotary motion of the carrier 44.
- the connecting mechanism A further comprises a bell crank 46 rotatably supported by a pair of axially spaced needle bearings 55 which are coupled within a pair of axially spaced brackets 44b of carrier 44, a first link 47 arranged between slider 43 and bell crank 46, and a second link 48 arranged between operation rods 21 and operatively interconnected to bell crank 46.
- the input shaft 41 is provided thereon with a ball nut 41a which has a rack portion 41b in mesh with a toothed portion 42b of sector gear 42.
- the slider 43 is in the form of a cylindrical piston which is formed at one side thereof with a rack portion 43a in mesh with another toothed portion 42c of sector gear 42.
- the carrier 44 has a cylindrical gear member secured to the rear end thereof and formed with a toothed portion 44a.
- the drive means 45 includes a pinion 45a in mesh with the toothed portion 44a of the cylindrical gear member, and a reversible electric motor 45b mounted on the housing 40 and drivingly connected to pinion 45a to effect rotary motion of the carrier 44 in accordance with the vehicle speed.
- the drive means 45 is conditioned to retain the carrier 44 in a neutral position where a rotational axis L 3 of bell crank 46 coincides with the axis L 1 of operation rods 21.
- the bell crank 46 is integrally provided with first and second arms 46a, 46b which are arranged to respectively extend downward and along the axis L 2 of slider 43 when the carrier 44 is being retained in the neutral position.
- the first link 47 has a rear end 47a pivotally connected with slider 43 by means of a ball joint 61 and a front end pivotally connected with a swingable end of first arm 46a of bell crank 46 by means of a ball joint 62.
- the first link 47 is arranged in such a manner that when the carrier 44 is retained in the neutral position, an axis line L 4 between respective centers of ball joints 61 and 62 makes an angle of approximately 90° with an axis line L 5 between the rotational axis L 3 of bell crank 46 and the center of ball joint 62.
- the second link 48 has a central portion 48a slidably and pivotally connected with the second arm 46b of bell crank 46 thrcugh a spherical bearing 56 and opposite ends 48b, 48c each pivotally connected with the operation rods 21 by mears of ball joints 63 and 64 located on the axis L 1 .
- the sector gear 42 is rotated counterclockwisely or clockwisely in response to rotation of the input shaft 41 to effect forward or backward movement of the slider 43, and in turn, the bell crank 46 is rotated clockwisely or counterclockwisely, as viewed in Fig. 4.
- This causes only a conical motion of second link 48 about the axis L 1 of operation rods 21 but does not cause any lateral movement of second link 48. It is, therefore, able to retain the rear road wheels WR in their neutral positions even when the front road wheels WF are steered to the right or left.
- the rotational axis L 3 of bell crank 46 makes an angle of 90 0 with the axis L 1 of operation rods 21.
- the bell crank 46 is rotated counterclockwisely or clockwisely in response to forward or backward movement of the slider 43, as viewed in Fig. 3.
- This causes leftward or rightward displacement of second link 48 along the axis L 1 of operation rods 21 to steer the rear road wheels WR to the right or left. It is, therefore, able to steer the rear road wheels WR in the same direction as that of the front road wheels WF.
- the above-described operation is effected in a condition where the rotational axis L 3 of bell crank 46 is inclined rightward at an angle with respect to a standard plane including the axis L 1 of operation rods 21 and the rotational axis L 2 of carrier 44.
- a common plane in parallel with the standard plane may be defined as a standard plane.
- the ratio of the steering angle of the rear road wheels WR relative to that of the front road wheels WF is determined by the inclined angle of the rotational axis L 3 of bell crank 46 to the axis L 1 of operation rds 21 and becomes a maximum value when the inclined angle is 90°.
- the rotational axis L 3 of bell crank 46 makes an angle of 90 4 with the axis L 1 of operation rods 21.
- the bell crank 46 is rotated clockwisely or counterclockwisely in response to forward or backward movement of the slider 43, as viewed in Fig. 3.
- This causes rightward or leftward displacement of second link 48 along the axis L 1 of operation rods 21 to steer the rear road wheels WR to the left or right, It is, therefore, able to steer the rear road wheels WR in an opposite direction to that of the front road wheels WF.
- This operation is effected in a condition where the rotational axis L 3 of bell crank 46 is inclined leftward at an angle with respect to the standard plane including the axis L 1 of operation rods 21 and the rotational axis L 2 of carrier 44.
- the ratio of the steering angle of the rear road wheels WR relative to that of the front road wheels WF is determined by the inclined angle of the rotational axis L 3 of bell crank 46 to the axis L 1 of operation rds 21 and becomes a maximum value when the inclined angle is 90°.
- the electric motor 45b of drive means 45 is controlled to rotate the carrier 44 about the axis L 2 of slider 43 in accordance with the vehicle speed.
- the direction and angle of the rotational axis L 3 of bell crank 46 can be varied to control the steering angle ratio and direction of the rear road wheels WF relative to the front road wheels WF in accordance with the vehicle speed.
- the first arm 46a of bell crank 46 is connected to the first link 47 in such a manner that the axis line L 4 between ball joints 61, 62 makes an angle of approximately 90° with the axis line L 5 between the rotation axis L 3 of bell crank 46 and the center of ball joint 62, and the second arm 46b of bell crank 46 is axially slidably coupled with the central portion 48a of second link 48.
- a rotation angle 9 of second arm 46b caused by forward movement of first link 47 in a predetermined distance S becomes substantially equal to a rotation angle 8 of second arm 46b caused by backward movement of first link 47 in the same distance S.
- the axial novement amount of operation rods 21 in one direction caused by rotation of the input shaft 41 can be made substantially equal to that of operation rods 21 in the opposite direction caused by reverse rotation of the input shaft 41.
- the connectinc mechanism A may be modified as follows.
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- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Transportation (AREA)
- Mechanical Engineering (AREA)
- Steering-Linkage Mechanisms And Four-Wheel Steering (AREA)
Abstract
Description
- The present invention relates to a steering system for an automotive vehicle having two pairs of dirigible road wheels, and more particularly to a rear wheel steering mechanism adapted for use in a four-wheel steering system capable of steering the dirigible rear road wheels in response to steering operation of the dirigible front road wheals.
- In such a four-wheel steering system as described above, there is provided a linkage such as a rotary shaft or a reciprooable link arranged in a fore-and-aft direction of the vehicle and drivingly connected at its front end to a front wheel steering mechanism to be moved in response to steering operation thereof, and a connecting mechanism arranged to drivingly connect the linkage to an operation rod of a rear wheel steering mechanism in such a manner that the operation rod is displaced in an axial direction in response to movement of the linkage to steer the dirigible rear road wheels. In Japanese Patent Early Publications Nos. 59-26363, 59-26364 and 59-26365, there has been proposed such a connecting mechanism adapted for use in combination with the rear wheel steering mechanism, wherein the connecting mechanism is designed to vary the ratio of the steering angle of the rear road wheels relative to that of the front road wheels and to vary the steering direction of the rear road wheels relative to that of the front road wheels. The connecting mechanism includes an input shaft in drive connection to the linkage for rotation therewith, an output shaft swingably connected at its one end to the input shaft by means of a universal joint and being integrally connected at its other end with an operation rod of the rear wheel steering mechanism, and drive means arranged to incline the output shaft with respect to the input shaft. In operation of the connecting mechanism, an inclined angle of the output shaft with respect to the input shaft is controlled by activation of the drive means to vary the steering angle ratio and direction of the rear road wheels. In such control of the output shaft, however, the operation rod of the rear wheel steering mechanism is inevitably displaced in an axial direction even when the input shaft is being stat:onary. This causes change in the alignment, particularly toe-in, of the rear road wheels, resulting in deterioration of the steering stability of the vehicle.
- It is, therefore, a primary object of the present invention to provide an improved connecting mechanism adapted for use in combination with the rear wheel steering mechanism, wherein the steering angle and direction of the rear road wheels relative to those of the front road wheels ear be controllod without oaucing any change in the alignment of the rear road wheels.
- A secondary object of the present invention is to provide an improved ccnnecting mechanism, having the above-described characteristics, wherein the ratio of the steering angle of the rear road wheels relative to that of the front road wheels can be controlled in accordance with the vehicle speed.
- According to the present invention, the foregoing objects are accomplished by providing a connecting mechanism assembled in combination with the rear wheel steering mechanism and being drivingly connected to the front wheel steering mechanism through a linkage for effecting axial movement of an operation rod of the rear wheel steering mechanism in response to operation of the front wheel steering mechanism. The connecting mechanism comprises a housing arranged to fixedly mounted on a body structure of the vehicle, a carrier rotatably mounted within the housing and being arranged to rotate about a first axis perpendicular to the axis of the operation rod, drive means mounted on the housing to effect rotary motion of the carrier about the first axis, a bell crank rotatably mounted on the carrier and arranged to rotate about a second axis coaxial or in parallel with the axis of the operation rod when the carrier is retained in a neutral position, the bell crank having a first arm extending therefrom at a predetermined angle to the first axis and a second arm extending therefrom along the first axis, a first link having one end pivotally connected vith the first arm of the bell crank and the other end operatively connected to the linkage to be moved along the first axis in response to operation of the front wheel steering mechanism, and a second link pivotally connected with the second arm of the bell crank and operatively connected to the operation rod.
- Preferably, the connecting mechanism further comprises an input shaft rotatably mounted within the housing and being drivingly connected to the front wheel steering mechanism through the linkage to be rotated in response to operation of the front wheel steering mechanism, and a slider slidably mounted within the housing along the first axis and pivotally connected to the other end of the first link, the slider being operatively connected to the input shaft to be reciprocated along the first axis in response to rotation of the input shaft.
- For a better understanding of the present invention, and to show how the same may be carried into effect, reference will now be made, by way of example, to the accmpanying drawings, in which:
- Fig. 1 is a schematic plan view of a four-wheel steering system including a connecting mechanism assembled in combination with a rear wheel steering mechanism in accordance vith the present invention;
- Fig. 2 is a rear elevation of the connecting mechanism shown in Fig. 1;
- Fig. 3 is an enlarged cross-sectional plan view taken along line III-III in Fig. 2;
- Fig. 4 is a fragmentary cross-sectional side view taken along line IV-IV in Fig. 3; and
- Fig. 5 is an enlarged fragmentary cross-sectional plan viev of a modification of the connecting mechanism.
- Referring now to the drawings, particularly in Fig. 1, there is schematically illustrated an automotive vehicle equipped with a four-wheel steering system which comprises a front
wheel steering mechanism 10 interconnected with a rearwheel steering mechanism 20 by means of alinkage 30. the frontwheel steering mechanism 10 is in the form of a well-known steering mechanism which includes arack bar 11 arranged to be axially displaced by operation of a steering wheel WS, a pair oftie rods 13 each connected to opposite ends ofrack bar 11, and a pair ofknuckle arms 12 each connected to thetie rods 13 to steer a pair of dirigible front road wheels WF in response to axial displacement of therack bar 11. As shown in Figs. 1 to 3, the rearwheel steering mechanism 20 includes a pair ofoperation rods 21 arranged to be displaced along with a lateral axis L1, a pair oftie rods 23 each connected to theoperation rods 21, and a pair ofknuckle arms 22 each connected to thetie rods 23 to steer a pair of dirigible rear road wheels WR in response to axial movement of theoperation rods 21. - The
linkage 30 includes a mainrotary shaft 31 arranged in a fore-and-aft direction of the vehicle and rotatably supported on a body structure of the vehicle. The mainrotary shaft 31 has one end drivingly connected to afront pinion shaft 34 through anintermediate shaft 32 and the other end drivingly connected through an intermediate shaft 33 to a connecting mechanism A assembled in combination with the rearwheel steering mechanism 20. Thefront pinion shaft 34 is drivingly connected to therack bar 11 to be rotated in response to axial displacement of therack bar 11. - As shown in Figs. 1 to 4, the connecting mechanism A comprises a housing 40'fixedly mounted on the vehicle body structure, an
input shaft 41 rotatably supported by a pair of axially spacedball bearings housing 40 and being arranged in drive connection to thelinkage 30, asector gear 42 pivotally mounted withinhousing 40 at its axis part 42a, aslider 43 axially slidably mounted within acylindrical bore 40a ofhousing 40 the axis L2 of which is located in the fore-and-aft direction of the vehicle and perpendicularly to the axis L1 ofoperation rods 21, acylindrical carrier 44 rotatably supported by a pair of axially spacedball bearings housing 40 and being arranged to rotate about the axis L2 ofslider 43, and a drive means 45 mounted on thehousing 40 to effect rotary motion of thecarrier 44. The connecting mechanism A further comprises abell crank 46 rotatably supported by a pair of axially spacedneedle bearings 55 which are coupled within a pair of axially spacedbrackets 44b ofcarrier 44, afirst link 47 arranged betweenslider 43 andbell crank 46, and asecond link 48 arranged betweenoperation rods 21 and operatively interconnected tobell crank 46. - As shown in Fig. 3, the
input shaft 41 is provided thereon with aball nut 41a which has a rack portion 41b in mesh with a toothed portion 42b ofsector gear 42. Theslider 43 is in the form of a cylindrical piston which is formed at one side thereof with arack portion 43a in mesh with another toothed portion 42c ofsector gear 42. Thecarrier 44 has a cylindrical gear member secured to the rear end thereof and formed with atoothed portion 44a. The drive means 45 includes apinion 45a in mesh with thetoothed portion 44a of the cylindrical gear member, and a reversible electric motor 45b mounted on thehousing 40 and drivingly connected topinion 45a to effect rotary motion of thecarrier 44 in accordance with the vehicle speed. When the front and rearwheel steering mechanisms carrier 44 in a neutral position where a rotational axis L3 ofbell crank 46 coincides with the axis L1 ofoperation rods 21. As shown in Fig. 4, thebell crank 46 is integrally provided with first andsecond arms 46a, 46b which are arranged to respectively extend downward and along the axis L2 ofslider 43 when thecarrier 44 is being retained in the neutral position. - The
first link 47 has a rear end 47a pivotally connected withslider 43 by means of aball joint 61 and a front end pivotally connected with a swingable end of first arm 46a ofbell crank 46 by means of aball joint 62. In this embodiment, thefirst link 47 is arranged in such a manner that when thecarrier 44 is retained in the neutral position, an axis line L4 between respective centers ofball joints bell crank 46 and the center ofball joint 62. Thesecond link 48 has acentral portion 48a slidably and pivotally connected with thesecond arm 46b ofbell crank 46 thrcugh aspherical bearing 56 andopposite ends operation rods 21 by mears ofball joints - Hereinafter, the operation of the four-wheel steering system will be described in detail. When the steering wheel WS is operated to turn the vehicle to the right or left, the
rack tar 11 is displaced in a lateral direction to steer the front road wheels WF and to rotate theinput shaft 41 of connecting mechanism A through thelinkage 30. Assuming that thecarrier 44 is being retained in the neutral position during rotation of theinput shaft 41, the rotational axis L3 ofbell crank 46 is maintained to coincide with the axis L1 ofoperation rods 21. In such a condition, thesector gear 42 is rotated counterclockwisely or clockwisely in response to rotation of theinput shaft 41 to effect forward or backward movement of theslider 43, and in turn, thebell crank 46 is rotated clockwisely or counterclockwisely, as viewed in Fig. 4. This causes only a conical motion ofsecond link 48 about the axis L1 ofoperation rods 21 but does not cause any lateral movement ofsecond link 48. It is, therefore, able to retain the rear road wheels WR in their neutral positions even when the front road wheels WF are steered to the right or left. - Assuming that the drive means 45 is activated to rotate the
carrier 44 counterclowisely by 90°, the rotational axis L3 ofbell crank 46 makes an angle of 900 with the axis L1 ofoperation rods 21. In such a condition, thebell crank 46 is rotated counterclockwisely or clockwisely in response to forward or backward movement of theslider 43, as viewed in Fig. 3. This causes leftward or rightward displacement ofsecond link 48 along the axis L1 ofoperation rods 21 to steer the rear road wheels WR to the right or left. It is, therefore, able to steer the rear road wheels WR in the same direction as that of the front road wheels WF. The above-described operation is effected in a condition where the rotational axis L3 ofbell crank 46 is inclined rightward at an angle with respect to a standard plane including the axis L1 ofoperation rods 21 and the rotational axis L2 ofcarrier 44. In general, a common plane in parallel with the standard plane may be defined as a standard plane. In addition, the ratio of the steering angle of the rear road wheels WR relative to that of the front road wheels WF is determined by the inclined angle of the rotational axis L3 ofbell crank 46 to the axis L1 ofoperation rds 21 and becomes a maximum value when the inclined angle is 90°. - Assuming that the drive means 45.is activated to rotate the
carrier 44 clockwisely from the neutral position by 90', the rotational axis L3 ofbell crank 46 makes an angle of 904 with the axis L1 ofoperation rods 21. In such a condition, thebell crank 46 is rotated clockwisely or counterclockwisely in response to forward or backward movement of theslider 43, as viewed in Fig. 3. This causes rightward or leftward displacement ofsecond link 48 along the axis L1 ofoperation rods 21 to steer the rear road wheels WR to the left or right, It is, therefore, able to steer the rear road wheels WR in an opposite direction to that of the front road wheels WF. This operation is effected in a condition where the rotational axis L3 ofbell crank 46 is inclined leftward at an angle with respect to the standard plane including the axis L1 ofoperation rods 21 and the rotational axis L2 ofcarrier 44. In addition, the ratio of the steering angle of the rear road wheels WR relative to that of the front road wheels WF is determined by the inclined angle of the rotational axis L3 ofbell crank 46 to the axis L1 ofoperation rds 21 and becomes a maximum value when the inclined angle is 90°. - In a practical embodiment of the present invention, it is desirable that the electric motor 45b of drive means 45 is controlled to rotate the
carrier 44 about the axis L2 ofslider 43 in accordance with the vehicle speed. With such control of the electric motor 45b of drive means 45, the direction and angle of the rotational axis L3 ofbell crank 46 can be varied to control the steering angle ratio and direction of the rear road wheels WF relative to the front road wheels WF in accordance with the vehicle speed. When thecarrier 44 is rotated in a condition shown in the figure to vary the direction and angle of the rotational axis L3 ofbell crank 46, thebell crank 46 rotates withcarrier 44 to cause a conical motion of thefirst link 47 with an apex atball joint 61, while thesecond link 48 is retained in position to avoid lateral movement of theoperation rods 21 along the axis L1. This is effective to ensure the steering stability of the vehicle without causing any change in the alignment of rear road wheels WR. - Furthermore, in the above embodiment, the first arm 46a of
bell crank 46 is connected to thefirst link 47 in such a manner that the axis line L4 betweenball joints bell crank 46 and the center ofball joint 62, and thesecond arm 46b ofbell crank 46 is axially slidably coupled with thecentral portion 48a ofsecond link 48. With such arrangement of thebell crank 46, a rotation angle 9 ofsecond arm 46b caused by forward movement offirst link 47 in a predetermined distance S becomes substantially equal to a rotation angle 8 ofsecond arm 46b caused by backward movement offirst link 47 in the same distance S. As a result, in operation of the rearwheel steering mechanism 20, the axial novement amount ofoperation rods 21 in one direction caused by rotation of theinput shaft 41 can be made substantially equal to that ofoperation rods 21 in the opposite direction caused by reverse rotation of theinput shaft 41. - In practical embodiments of the present invention, the connectinc mechanism A may be modified as follows.
- 1) Although in the embodiment described above the
input shaft 41,sector gear 42 andslider 43 have been provided to effect axial movement of thefirst link 47 in response to rotation of the mainrotary shaft 31 oflinkage 30, thelinkage 30 may be replaced with a reciprocable linkage to directly effect axial movement of thefirst link 47 in response to operation of the frontwheel steering mechanism 10. In such a modification, it is able to eliminate theinput shaft 41,sector gear 42,slider 43 and the component parts associated therewith. - 2) Although in the embodiment described above, the
second link 48 has been provided to connect thesecond arm 46b ofbell crank 46 to the pair ofoperation rods 21, theoperation rcds 21 may be replaced with asingle operation rod 121 as shown in Fig. 5. In such a modification, theoperation rod 121 is connected at opposite ends thereof with thetie rods 23 shown in Fig. 1, and the second link 4E is replaced with anarm member 148 which is connected at one end thereof with anarm 121a ofoperation rod 121 through apin joint 165 and pivotally connected at the other end thereof with a second arm 146b of abell crank 146 by means of aball joint 166. Thepin joint 165 includes a pair of axially spacedradial bearings 165a, 165b and a pair of axially spacedthrust bearings 165c, l65d which are arranged to permit rotation of thearm member 148 relative to thearm 121a ofoperation rod 121 about the rotational axis L3 ofbell crank 146. In this modification, the rotational axis L3 ofbell crank 146 is displaced in a distance from the axis L1 ofoperation rod 121 to avoid interference between bell crank 146 andoperation rod 121. - 3) In the modification shown in Fig. 5, an angle between the
first link 47 and the first arm ofbell crank 146 is determined in consideration with an angle between the axis L2 ofslider 43 and a line connecting opposite ends ofarm member 148. With such arrangement of the bell crank 146, the axial movement amount ofoperation rod 121 in one direction from a neutral position can be made substantially equal to that ofoperation rod 121 in the opposite direction from the neutral position.
Claims (6)
wherein said connecting mechanism comprises:
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP84400/85U | 1985-06-04 | ||
JP1985084400U JPH0351259Y2 (en) | 1985-06-04 | 1985-06-04 |
Publications (3)
Publication Number | Publication Date |
---|---|
EP0204305A2 true EP0204305A2 (en) | 1986-12-10 |
EP0204305A3 EP0204305A3 (en) | 1987-07-22 |
EP0204305B1 EP0204305B1 (en) | 1989-04-26 |
Family
ID=13829525
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP86107496A Expired EP0204305B1 (en) | 1985-06-04 | 1986-06-03 | Four-wheel steering system for automotive vehicles |
Country Status (4)
Country | Link |
---|---|
US (1) | US4691932A (en) |
EP (1) | EP0204305B1 (en) |
JP (1) | JPH0351259Y2 (en) |
DE (1) | DE3663013D1 (en) |
Cited By (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0308042A2 (en) * | 1987-09-11 | 1989-03-22 | STEWART & STEVENSON SERVICES, INC. | Vehicle steering system |
DE4201906A1 (en) * | 1991-01-25 | 1992-07-30 | Honda Motor Co Ltd | STEERING DEVICE WITH CHANGEABLE STEERING ANGLE RATIO |
Families Citing this family (9)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
DE3776504D1 (en) * | 1986-11-26 | 1992-03-12 | Toyota Motor Co Ltd | FOUR-WHEEL STEERING SYSTEM FOR CYCLING VEHICLES. |
JPH064422B2 (en) * | 1987-01-09 | 1994-01-19 | マツダ株式会社 | 4-wheel steering system for vehicles |
JPH0725324B2 (en) * | 1987-12-28 | 1995-03-22 | ダイハツ工業株式会社 | Rear wheel steering mechanism |
JPH026275A (en) * | 1988-06-23 | 1990-01-10 | Honda Motor Co Ltd | Device for steering front/area wheel of vehicle |
US4826188A (en) * | 1988-07-05 | 1989-05-02 | Chrysler Motors Corporation | Rear wheel steering drive mechanism |
US4813694A (en) * | 1988-07-06 | 1989-03-21 | Chrysler Motors Corporation | Rear wheel steering drive mechanism |
DE3910385A1 (en) * | 1988-12-01 | 1990-06-07 | Bosch Gmbh Robert | Steering gear |
JPH03136975A (en) * | 1989-10-24 | 1991-06-11 | Atsugi Unisia Corp | Rear-wheel steering device of front-and-rear-wheel steering vehicle |
US5076597A (en) * | 1989-12-21 | 1991-12-31 | Daihatsu Motor Co., Ltd. | Four-wheel steering system for vehicle |
Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5926363A (en) * | 1982-08-02 | 1984-02-10 | Honda Motor Co Ltd | Steering apparatus for car |
JPS5926364A (en) * | 1982-08-02 | 1984-02-10 | Honda Motor Co Ltd | Steering apparatus for car |
JPS5926365A (en) * | 1982-08-02 | 1984-02-10 | Honda Motor Co Ltd | Joint and steering apparatus for car |
Family Cites Families (5)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US3716110A (en) * | 1970-07-22 | 1973-02-13 | A Fonda | Steering and directing mechanism |
JPS5261024A (en) * | 1975-11-13 | 1977-05-20 | Takemochi Ishii | Steering control system for fourrwheel steered vehicle |
JPS6044185B2 (en) * | 1978-12-29 | 1985-10-02 | 本田技研工業株式会社 | Vehicle steering method and device |
JPS5992261A (en) * | 1982-11-15 | 1984-05-28 | Mazda Motor Corp | 4-wheeled steering device for vehicle |
JPS60193771A (en) * | 1984-03-15 | 1985-10-02 | Mazda Motor Corp | 4-wheels steering apparatus for car |
-
1985
- 1985-06-04 JP JP1985084400U patent/JPH0351259Y2/ja not_active Expired
-
1986
- 1986-06-03 DE DE8686107496T patent/DE3663013D1/en not_active Expired
- 1986-06-03 US US06/869,891 patent/US4691932A/en not_active Expired - Fee Related
- 1986-06-03 EP EP86107496A patent/EP0204305B1/en not_active Expired
Patent Citations (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JPS5926363A (en) * | 1982-08-02 | 1984-02-10 | Honda Motor Co Ltd | Steering apparatus for car |
JPS5926364A (en) * | 1982-08-02 | 1984-02-10 | Honda Motor Co Ltd | Steering apparatus for car |
JPS5926365A (en) * | 1982-08-02 | 1984-02-10 | Honda Motor Co Ltd | Joint and steering apparatus for car |
Non-Patent Citations (3)
Title |
---|
PATENT ABSTRACTS OF JAPAN, vol. 8, no. 120 (M-300)[1557], 6th June 1984; & JP-A-59 026364 (HONDA GIKEN KOGYO K.K.) 10-02-1984 * |
PATENT ABSTRACTS OF JAPAN, vol. 8, no. 120 (M-300)[1557], 6th June 1984; & JP-A-59 026365 (HONDA GIKEN KOGYO K.K.) 10-02-1984 * |
PATENT ABSTRACTS OF JAPAN, vol. 8, no. 120, (M-300)[1557], 6th June 1984; & JP-A-59 026363 (HONDA GIKEN KOGYO K.K.) 10-02-1984 * |
Cited By (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
EP0308042A2 (en) * | 1987-09-11 | 1989-03-22 | STEWART & STEVENSON SERVICES, INC. | Vehicle steering system |
EP0308042A3 (en) * | 1987-09-11 | 1990-01-17 | STEWART & STEVENSON SERVICES, INC. | Vehicle steering system |
DE4201906A1 (en) * | 1991-01-25 | 1992-07-30 | Honda Motor Co Ltd | STEERING DEVICE WITH CHANGEABLE STEERING ANGLE RATIO |
DE4201906C2 (en) * | 1991-01-25 | 1998-11-26 | Honda Motor Co Ltd | Device for steering a steerable wheel by turning a steering wheel |
Also Published As
Publication number | Publication date |
---|---|
EP0204305B1 (en) | 1989-04-26 |
US4691932A (en) | 1987-09-08 |
JPS61199477U (en) | 1986-12-13 |
EP0204305A3 (en) | 1987-07-22 |
DE3663013D1 (en) | 1989-06-08 |
JPH0351259Y2 (en) | 1991-11-01 |
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